Pulsed tissue Doppler imaging for the detection of myocardial ischaemia, a comparison with myocardial perfusion SPECT

Exercise-induced changes in E/E' ratio in patients with suspected coronary artery disease

OBJECTIVES

Ischemia affects the left ventricular (LV) diastolic function earlier than the systolic function. The ratio of the early diastolic transmitral velocity to the early diastolic tissue velocity (E/E') measured by tissue Doppler echocardiography allows a reliable assessment of the diastolic function. We investigated whether exercise-induced changes in E/E' ratio may help in the detection of coronary artery disease (CAD).

METHODS

The study population consisted of 114 patients undergoing coronary angiography. Patients with impaired LV ejection fraction, earlier myocardial infarction, arterial hypertension greater than stage I, or LV hypertrophy were excluded. Patients underwent a treadmill exercise test combined with an echocardiogram at baseline and within the first minute after exercise.

RESULTS

Coronary angiography showed a stenosis more than 70% in 72 (63%) patients (CAD group), the remaining 42 formed the non-CAD group. The two groups did not differ regarding age, sex, LV dimensions, and function. At baseline, the E/E' lateral and septal ratios and their average did not differ between the two groups. The exercise-induced changes of the E/E' ratios were higher in the CAD group (change of E/E' average: 1.9+/-3.3 vs. -1.1+/-2.3, P<0.001). In the CAD group, 78% showed an exercise-induced increase of E/E' average compared with 24% in the non-CAD group (P<0.001). In multivariate analysis, the association between an increase of E/E' average and the presence of obstructive CAD was independent of traditional risk factors, exercise test result or exercise-induced wall motion abnormalities (odds ratio=8.1, P<0.001).

CONCLUSION

Exercise-induced changes in E/E' ratio may offer significant assistance in the detection of CAD.

Assessment of Myocardial Velocities and Global Function of the Left Ventricle in Asymptomatic Patients with Moderate-to-Severe Chronic Aortic Regurgitation: A Tissue Doppler Echocardiographic Study

OBJECTIVE

Asymptomatic patients with chronic aortic regurgitation (AR) have an excellent prognosis in the presence of preserved systolic function. It is a challenge to recognize patients with subclinical myocardial dysfunction in AR. Conventional parameters still have many drawbacks in predicting early left ventricular (LV) dysfunction. Pulsed-wave tissue Doppler imaging (PW-TDI) is a useful noninvasive technique for evaluating global and regional LV systolic function. In this study, we aimed to assess clinical usefulness of TDI in predicting early disturbance of myocardial contractility in asymptomatic patients with significant AR and preserved left ventricular systolic function.

METHODS AND THE RESULTS

Echocardiograms were obtained in 32 AR patients and 33 healthy subjects. In addition to conventional parameters, regional myocardial velocities, isovolumetric contraction time (mICT), isovolumetric relaxation time (mIRT), and ejection time (mET) of left ventricle were obtained by TDI and modified LV myocardial performance index (MPI) was calculated. In AR, peak systolic velocity (Sm) of septal and anterior mitral annulus, and mean Sm was significantly lower, and LVMPI was significantly higher compared to control group.

CONCLUSION

The data obtained by TDI show that LV MPI is lengthened, and systolic myocardial velocities are shortened in patients having chronic AR with normal LV systolic function according to conventional echocardiographic parameters. This suggests that LV long-axis contraction and global LV performance are preciously and noticeably decreased in patients with moderate-to-severe chronic AR despite normal LV ejection fraction.

Stress echocardiography for the diagnosis of coronary artery disease: progress towards quantification

PURPOSE OF REVIEW

This review highlights recent progress in the quantitative approach to the interpretation of stress echocardiograms. Recent literature regarding the application of tissue Doppler and strain rate imaging for the diagnosis of coronary artery disease is summarized.

RECENT FINDINGS

The high temporal and spatial resolution of tissue Doppler and strain rate imaging permit recognition of regional myocardial dysfunction. These techniques have been performed during low- and high-dose dobutamine stress echocardiography and have been applied to exercise echocardiography. During stress, the peak systolic velocity and early diastolic velocity increased to a greater degree in normal segments compared to ischemic segments. With tissue Doppler imaging, viable segments show increases in systolic velocities in contrast to infarcted segments. Presently, the feasibility of strain rate imaging is slightly less than that of conventional wall motion assessment. However, in preliminary studies, tissue Doppler parameters and especially strain rate parameters appear to offer advantages in accuracy compared to conventional wall motion assessment.

SUMMARY

Tissue Doppler and strain rate imaging offer great promise for the accurate, reproducible quantification of regional myocardial function. Further studies are indicated to prove their accuracy, efficiency, and superiority over existing methods.